Haemophilia (also spelled hemophilia in North America, from the Greek haima αἷμα 'blood' and philia φιλος 'friend') is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A (clotting factor VIII deficiency) is the most common form of the disorder, occurring at about 1 in 5,000–10,000 male births. Haemophilia B (fa...
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Haemophilia (also spelled hemophilia in North America, from the Greek haima αἷμα 'blood' and philia φιλος 'friend') is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A (clotting factor VIII deficiency) is the most common form of the disorder, occurring at about 1 in 5,000–10,000 male births. Haemophilia B (factor IX deficiency) occurs at about 1 in about 20,000–34,000 male births.
Similarly to most recessive sex-linked, X chromosome disorders, only males typically exhibit symptoms. This is due to the fact that females have two X chromosomes while males have only one, lacking a 'back up' copy for the defective gene the defective gene becomes manifest more easily in males. Because females have two X chromosomes and because haemophilia is rare, the chance of a female having two defective copies of the gene is very low, thus females are almost...
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